This opera about cosmetic surgery is unremittingly dreadful - the musical equivalent of waterboarding. There's a lot you could say about vanity, appearance, the perception of self, the fact that it's what lies beneath that matters. Unfortunately, Skin Deep doesn't explore any of this.

In Armando Iannucci's libretto, cosmetic surgeon Dr Needlemeier performs yearly operations on his wife at his Alpine clinic, falls in lust with his disfigured receptionist and develops an elixir of youth for which the missing ingredient is a famous person's testicle.

There probably are some surgeons as self-congratulatory as Needlemeier (it takes self-confidence to perform any surgery), and I have met surgeons who operate on their wives, though it is considered unethical. In one scene, Needlemeier does a swap: his receptionist gets his wife's face, and vice versa. The scene is well handled, but it leaves questions: does he now love the one that looks like the one he loves, or does he love the one that doesn't? It's very confusing.

Needlemeier's elixir of life makes everyone look the same. That cosmetic surgery does this is utter nonsense. Neither is it frivolous and celebrity-obsessed. Most people who come for cosmetic surgery are ordinary working-class people who, like all of us, dislike something about themselves.

The moment that's just too much to bear comes when the characters decide they don't need the elixir, revert to their wrinkly, saggy-breasted bodies, and sing banal homilies about how it's better to look the way God intended us to, and let's admire each other for our imperfections. Of course it is. Cosmetic surgery doesn't go against such thinking for a moment.

• Professor Simon Kay is a consultant plastic surgeon with Leeds Teaching Hospitals NHS Trust. Skin Deep is at the Grand Theatre, Leeds (0113-222 6222), on Wednesday and on 11 February. Then touring.